U.S. weather forecasters say Hurricane Sergio has strengthened off Mexico's Pacific coast and could come closer to land in the coming days.

The National Hurricane Center in Miami said Wednesday that Sergio has become a Category Two storm with wind speeds increasing to 158 kilometers per hour.

The forecasters say the storm is more than 700 kilometers south of the tourist town of Manzanillo. Sergio is expected to move slowly northward, staying over water for the next five days, but could move close to the coast.

Two Pacific hurricanes made landfall in Mexico in September. Sergio is the 10th hurricane in the eastern Pacific region this year.